1. Field of the Invention
The present invention relates to a slider sliding in an arc-shaped rail shaped from a metal plate-like member.
2. Description of the Related Art
Conventionally, there has been known an arc-shaped rail such as, for example, one for use in a walking assist device (for example, refer to Japanese Patent Laid-Open No. 2009-247605). This walking assist device has a seat member on which a user is seated in a straddling manner and a pair of left and right leg links that support the seat member from below. Each leg link is coupled to the seat member so as to be swingable in the front-rear direction relative to the seat member via a curve guide mechanism.
The curve guide mechanism includes an arc-shaped rail coupled to the rear end portion of a support frame of the seat member via a spindle extending in the front-rear direction so as to be swingable in the lateral direction and a slider sliding along the arc-shaped rail and fixed to the upper end portion of the leg link.
The arc-shaped rail includes: an inner peripheral wall on the inner peripheral side near the center of curvature; an outer peripheral wall on the outer peripheral side far from the center of curvature; a pair of side walls coupling the inner peripheral wall to the outer peripheral wall on both sides in the width direction (lateral direction) orthogonal to the longitudinal direction (front-rear direction) of the arc-shaped rail and to the direction of the radius of curvature (vertical direction) of the arc shape; and a slit formed in the central portion in the width direction of the outer peripheral wall, and the arc-shaped rail is formed with a C-shaped cross section. The outer peripheral wall is divided into two parts by the slit.
The slider has an insertion portion, which is inserted into the arc-shaped rail through the slit of the arc-shaped rail. The insertion portion has an inner rotating body in contact with the inner peripheral wall of the arc-shaped rail and an outer rotating body in contact with the outer peripheral wall of the arc-shaped rail.
A pair of outer rotating bodies are provided spaced apart from each other in the width direction of the arc-shaped rail so as to be in contact with a pair of outer peripheral walls divided by the slit.
The conventional arc-shaped rail has been shaped by extrusion molding by using aluminum in terms of weight reduction. The arc-shaped rail made of aluminum, however, has the problem of poor strength, though the weight reduction is achieved.
Therefore, it is conceivable to manufacture the arc-shaped rail by bending a metal plate-like member made of a high tension material (high-tensile steel plate) or the like by the spinning process or the like.
Further, it is conceivable to improve the wear resistance of the rotating bodies and the arc-shaped rail by increasing the number of rotating bodies of the slider to disperse a force transmitted between the slider and the arc-shaped rail.
Manufacturing the arc-shaped rail by bending the metal plate-like member, however, easily causes slight warpage of the respective walls due to a machining error or the like. In the case of slight warpage, some of the rotating bodies are unable to come in contact with the corresponding peripheral wall and the wear resistance is reduced.
Therefore, it is an object of the present invention to provide a slider capable of reducing the wear of the rotating bodies and the arc-shaped rail by bringing all rotating bodies into appropriate contact with the arc-shaped rail manufactured by using a metal plate-like member.